Any introduction needs to:
- give your reader a clear idea of what question you are answering in your paper
- invite your reader to Pin you in considering that question (that is, the introduction should appeal to the reader's interest)
- give a sense of why the question is important - to you and others
- give the reader an idea of what kinds of sources you are considering for evidence.
The introduction, then, presents a question, the context for asking that question, and your motivation for answering it.